10 reasons why this 228-point slump in the Dow makes me sit up and take notice

On Thursday, the day before the Japanese earthquake, the Dow Jones Industrial Average saw its biggest drop since August. Markets tumbled while fears surged -- about jobs, Spain and Saudi Arabia.

But what does this mean for you, the investor?

Was this just a one-day wonder, a buying opportunity, a small but passing cloud on an otherwise sunny horizon? Or was it something more ominous?

The Dow's Plunge: Should You Be Worried?